The changes in pitching mechanics and pitch velocity during a seven-inning simulated game in high school baseball pitchers [electronic resource] : a prospective descriptive study /

by Erkel, Jeremy J.

Abstract (Summary)

The Changes in Pitching Mechanics and Pitch Velocity During a Seven-Inning Simulated Game in High School Baseball Pitchers: A Prospective Descriptive Study. Jeremy J. Erkel Context: Past studies have described the pitching motion of youth, collegiate, or professional baseball pitchers, as well as the relationship between shoulder mechanics, extended play, and pitch velocity. However, there is little research that has described the changes in the pitching motion and pitch velocity as a result of increasing pitch counts in high school baseball pitchers. Objective: The purpose of this study was to describe how pitching mechanics change, when these changes occur, and the extent of which pitch velocities decline in high school baseball pitchers during a seven-inning simulated game. Design: This study was a prospective descriptive analysis of the pitching motion. The independent variables were a simulated game with 7 innings consisting of 12 pitches per inning and 9 minutes rest between innings. The dependent variables were shoulder, elbow, and trunk inclination angles, pitching mechanics analysis, and pitch velocity. Setting: The Caperton Indoor Practice Facility in Morgantown, WV. Patients and Other Participants: There were 4 subjects who were members of the boy’s varsity baseball team at Albert Gallatin High School. There was also one catcher whose sole purpose was to catch the pitches thrown by the subject. Subjects were obtained by a sample of convenience, 16.25 ± 0.50 years old, healthy, and had no history of shoulder or elbow pain or surgery within the past six months. Subjects were not included if they met the exclusion criteria of having a concussion in the past six months or a history of concussions that had altered or diminished their ability to balance on one leg. Intervention: Subjects pitched a seven-inning simulated baseball game that took place at the Caperton Indoor Practice Facility. Each subject pitched 7 innings consisting of 12 fastballs per inning from an indoor pitching mound. During the seven 12-pitch innings, two video cameras recorded each subject’s 1st, 7th, and 12th pitch of each inning. Foam markers were placed on lateral bony landmarks of the upper and lower extremity that aided in the analysis of joint angles of each subject’s pitching motion. A pitching evaluation checklist was also used to identify normal and/or abnormal pitching mechanics. Subjects also had their pitch velocity recorded using a radar gun for every pitch that was thrown. Those pitch speeds were recorded onto a chart and later used to describe how and when a subject’s pitch velocity changed as his pitch count increased during the course of the game. Main Outcomes Measures. Using joint angle measurements, shoulder internal rotation, shoulder external rotation, and shoulder abduction angles will decrease as pitch count increases. Also, elbow flexion and forward trunk tilt angles will decrease as pitch count increases using visual analysis. Lastly, average pitch velocity per inning will decrease as pitch count increases. Results: There was a significant difference within subjects in the shoulder internal rotation angles of Pitch #1 and Pitch #12 during the 1st inning of the 7-inning simulated game (F1,2 = 157.38, P < 0.05, ?2=0.994, ß=1.000). There was no significant difference within subjects between the mean shoulder abduction, external rotation, and trunk tilt angles at Pitch #1, #7, and #12 at each inning of the 7-inning simulated game. Mean within inning percent change scores were evident for all angles. Percent change scores between innings for all angles were evident, however these changes were not apparent for each of the 21 paired comparisons of innings. There was no significant difference in the mean pitch velocities of Pitch #1, #7, and #12 at each inning of the simulated game. There were minimal increases in mean within inning pitch velocity percent change scores during the 1st, 2nd, 3rd, 5th, and 6th innings, as well as small decreases within the 4th and 7th innings. The largest decrease in mean between inning pitch velocity percent change scores occurred between the 1st and 7th inning, and that the largest increase occurred between the 3rd and the 7th inning. Throughout the phases of the pitching motion, one abnormality occurred during the wind-up and follow-through phases, while no more than two were evident for the remaining phases of stride, arm cocking, acceleration, and deceleration. Conlcusion: Changes were observed in shoulder, elbow, and trunk kinematics during a simulated game in high school baseball pitchers. Furthermore, there were changes in pitch velocity as pitch counts increased during the simulated game. In the clinical setting, this study may serve as a guide for athletic trainers in the examination of proper vs. improper pitching mechanics at the shoulder, elbow, and trunk.